NetEq: Allow negative shift in BackgroundNoise::SaveParameters

NetEq: Allow negative shift in BackgroundNoise::SaveParameters

This change allows a shift factor to be negative.  This is the way it
was in the old (NetEq3) code; see
https://chromium.googlesource.com/external/webrtc/+/4d363ae305fa975e7f3ad2a5ca5dbe5e3f101f82/webrtc/modules/audio_coding/neteq/bgn_update.c,
lines 183-188.

Some input signals can lead to negative shifts, and would then trigger
an assert. The assert is now removed.

BUG=webrtc:4840
R=minyue@webrtc.org

Committed: https://chromium.googlesource.com/external/webrtc/+/3c4ef29140fb1a5e488899e1905a62277f0d9858

[hlundin-webrtc, 2015-08-25 13:30:23]

henrik.lundin@webrtc.org changed reviewers:
+ minyue@webrtc.org

[hlundin-webrtc, 2015-08-25 13:30:23]

Minyue,

Please, take a look at this CL. This fixes a diff that crept in during the NetEq
refactoring.

Thanks!

[minyue-webrtc, 2015-08-30 21:51:45]

lgtm

[hlundin-webrtc, 2015-08-31 05:41:26]

The CQ bit was checked by henrik.lundin@webrtc.org

[commit-bot: I haz the power, 2015-08-31 05:41:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1315833003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1315833003/1

[commit-bot: I haz the power, 2015-08-31 07:41:49]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-31 07:41:49]

Try jobs failed on following builders:
  android on tryserver.webrtc (JOB_TIMED_OUT, no build URL)

[hlundin-webrtc, 2015-08-31 08:18:50]

Committed patchset #1 (id:1) manually as
3c4ef29140fb1a5e488899e1905a62277f0d9858 (presubmit successful).